Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Crackpot perpetual energy generator idea

  1. Apr 6, 2003 #1
    Okay, this seems like it should work, but I know that it ought not too. Please tell me what you think.

    My idea is for a device which will be able to perpetually produce hydroelectric power. It works based on the ideas of cappilary action. Start with a large pool of water, and take a whole freaking ton of small tubes which water will travel up by capillary action. Have the water travel up the tubes and then form a new pool higher up, where a new batch of capillary tubes will be waiting to suck that water higher up, and the cycle goes on untill you reach a sufficient height. Here you cause the pool which has accumulated at the top level to fall off over an edge, go down and strike a rotor which works the same as any hydroelectric plant rotor works. After it strikes this the water returns to the original pool and the process repeats. And voila! (pretty sure that's spelled wrong) you have a perpetual energy generator!

    So tell me what you think!?!? I think the flaw to the idea is the part where the water comes out of the top of the cappillary pipes to make a new pool. But what do you think?
  2. jcsd
  3. Apr 6, 2003 #2
    I think the issues are 1) the tubes will fill with water, but not keep pulling up more after they're full, and 2) there is a max height you can pull water with up a given tube, and it likely takes a corresponding amount of energy to pull the water at the top out of the tube.
  4. Apr 6, 2003 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The main problem is that capillary action is a function of surface tension. While the height that water will rise in a tube is inversely proportional to the diameter of the tube, if the tube is shorter than this height, the water will rise to the top of the tube and no more.

    The water crawls up the tube because of the molecular attraction between the water and the wall of the tube. It can't climb up over the top of the tube, because there is no more wall to climb up.

    For this device to work, the water would have to spill up over the top of the tube, and capillary action won't cause this.
  5. Apr 6, 2003 #4
    Yes that's what I said my concern was. To bad it wouldn't work, it would be a great device if only you could get it to work! But then again there's a million things out there that would be great devices if only you could get them to work.
  6. Apr 9, 2003 #5
    What if the top of the tube turns down then widens out? The water would climb up turn and climb down, then lose attraction to the wall as it widens and drop in the pool.
  7. Apr 10, 2003 #6
    Well artman, i think the water will not be able to climb in a horizontal way (you know, at some point the tube will be horizontal for it to get down eventually).

    I have another good idea (based on this one).
    Suppose we were able to make some kind of pump that only sucks the water from the surface of the tube to put it into the container at that level, suppose the pump has effiecency of 100%.
    The energy needed to do so will be less than the energy needed to raise the water from the lower container to the upper one.
    So we will still have some kind of 'free energy' there (i know it is impossible, so there is some flaw in the logic that i don't see now).

    Any comments ?
  8. Apr 12, 2003 #7
    My gut tells me that the adhesive force that causes the capillary action in the first place will also act to resist your pump right at the surface you are trying to pull the water from. That is to say, not only are you pulling the water perhaps slightly up from the top of the tubes, but you also have to break the adhesive force from the tube to get the water into your pump.
  9. Apr 13, 2003 #8


    User Avatar

    And there is no such thing as a 100% efficient pump.
  10. Jul 15, 2006 #9
    ...I don't quite understand why Artman's arrangement won't work. (Not that I believe it will, I just don't understand why it won't.)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook